The 32-year-old, making his first start for the club since October due to injury, won the match with a deflected volley in the 64th minute to extend their lead at the top of the npower Championship.
"It is ours to lose from here on in," he told the South Wales Echo. "We've worked our socks off to get to this point. There are a lot of good teams, but the consistency we have had so far has got us to this point and we are going to work as hard as we can to try and keep the 10 points barrier.
"Nobody will take their foot off the gas. Everyone is desperate to play at the highest level, a lot haven't had that chance.
"It's driving us on so much that I can't see any complacency setting in."
With City out of this season's FA Cup after defeat to Macclesfield Malky Mackay has taken his squad out to Dubai for a five-day training camp to make the most of a gap in their fixture list but the former QPR striker is not expecting a week off in the sun.
"There will be a chance to relax, but it is very much a working trip," Smith said. "It would be stupid to treat it as a holiday."
- Sports & Recreation